Sheet metal flume trough



Nov. 27, 1934. A. 5. NORTON 1,982,064

SHEET METAL FLUME TROUGH Filed June 26, 1933 2 Sheets-Sheet l INVENTOR,

1934- A. c. NORTON SHEET METAL FLUME TROUGH Filed June 26, 1933 2 Sheets-Sheet 2 INVENTOR, 6185.0! Cl M Wat BY nhrrfv A TTORNEYS.

Patented Nov. 27, 1934 UNITED STA SHEET METAL FLUIVEE THOUGH Albert Colwell Norton, Berkeley, Calif., assignor to California Corrugated Culvert 00., Alameda County, Calif., a. corporation of California Application June 26, 1933, Serial No. 677,650

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1 This is a continuation in part of my application for Method of making sheet metal flume troughs, Serial No. 608,396, filed April 30th, 1932, 'nowv United States Letters Patent No. 1,937,663, I and relates to sheet metal troughs used in flumes for the transportation of water. Sheet metal flume troughs are commonly formed initially to semicircular cross section. It is well known in the art, however, that such 10. cross section is distorted under load, and tends to assume a curvature corresponding approximately to the hydraulic catenar'y. Such distortion is resisted to some extent by the stiffness of the sheet metal, and still more by the suspend- 15, mg rods and the transverse joints between adjacent trough sections, said joints usually including both transverse beads formed in the metal 'of the trough section and transverse clamping rods. The curvature of the trough also changes with variations in load, the deflection from the semicircle being greatest when the trough is about half full of water, and decreasing as the load approaches the maximum.

Distortion of initially semicircular sheet metal '28 flumes hascaused much annoyance and expense by producing leaks at the joints, especially at the ends of the fiume, where the sheet-metal trough joins rigid structures such as concrete head walls, and at horizontal bends or angles in the flume, as will be explained fully hereinafter.

Attempts have been made to overcome this leakage by forming the concrete structure to a theoretical catenary curvature where it is in contact with the sheet metal trough. Such attempts have not been successful, because of the fact that the curvature assumed by the loaded trough is not a true catenary, and cannot be calculated by any mathematical formula heretofore known.

I have found it possible to overcome the above described difficulties inherent in the semicircular sheet metal fiume, and to prevent leakage and loosening of the joints and suspension rods, by forming the trough initially to a curve which may be defined broadly as themean between the limits of distortion caused by variations in load,and which can be laid out about three major centers whose positions may be expressed as functions of the width across the top of the trough. I have also developed a simple and inexpensive method of forming the sheet to the compound curve above mentioned, as described and claimed in my United States Letters Patent No.,1,937,663 referred to above, all of which results in a fiume superior to those now in use. The. employment 5 of a sheet metal trough of compound curvatu also enables me to make important economies in the supporting substructure, as described and claimed in my United States Letters Patent No. 1,878,289, for fiumes.

My invention will now be described in, detail with reference to the accompanying drawings, it being understood that changes may be made, within the limits of the claims hereto appended, without departing from the spirit of the invention as defined in said claims.

In the draWings:- Fig. 1 is a part sectional plan of a flume embodying my improved trough, showing it connected with a concrete head wall at one end, and at another portion provided with a horizontal bend or angular deflection.

Fig. 2 is a transverse section of the same. Fig. 3 is a diagram illustrating the layout of the compound curve upon which the trough is formed, and showing the deflection from the semicircle and the limits thereof under varying loads. Fig. 4 is a plan view of the out blank or sheet from which the angle section shown in Fig. 1 is formed. v Referring more particularly to the drawings; the reference numeral 1 designates a trough formed from sheet metal with a rounded bottom 2 and divergent sides 3, the latter being curved inwardly upon a radius greater than that of said bottom. The trough is suspended by rods 4 extending transversely beneath it, the ends of said rods being secured to the frame or substructure, a conventional form of which is shown in Figs. 1

and 2 as comprising longitudinal stringers 5 and cross bars 6. In my improved construction, the upper portions of the sides 3 of the trough diverge at angles of about 16 degrees from the vertical, and the upper end portions of the rods 4, where they are attached to the frame, are also positioned at the same angle.

My trough 1 is formed of any suitable metal, preferably-galvanized sheet steel of the weight and stiffness ordinarily used in such structures. Its cross sectional shape is a compound curve drawn about three major centers, with narrow transition areas of changing radius connecting the major arcs. In the theoretical consideration of the curve, these transition areas may be ignored, however. The curve and its mathematical layout are illustrated diagrammatically in Fig.3, in which the heavy solid line 1a is the curve upon which the trough 1 is formed, 2a being thecentral arc of shorter radius and 3a the side arcs of longer radius, corresponding respectively to mum and minimum distortion, I reduce the longitudinal stress to that represented by the distance between the lines 14 and e, or 14 and I,

ficient extent, by making the sheet metal trough to the above described compound curve, which reduces its maximum possible load distortion to a negligible amount. The concrete head wall 7 should, of course, be formed to the same curve.

I claim:-

1. A flume trough comprising a sheet of metal initially bent upon an arc of compound curvature, the length of said are being equal to one half the circumference of a circle whose diameter is the width across the top of said trough, the radius of the side portions of said trough being greater than the radius of said circle, and the radius of the bottom portion being less than the radius of said circle.

2. A fiume trough comprising a sheet of metal initially bent to compound cross sectional curvature, the radius of the side portions of the trough being greater than one half the width across its top, and the radius of the bottom portion being less than one half said width.

ALBERT COLWELL NORTON. 

